Killing Floor is a delightful frolic with our English-speaking friends across the sea.
The graphics are quaint, really. They may not be as technically proficient as the modern connoisseur of the FPS has grown used to, but they harken a simpler time in our lives. A less complicated time when simply blowing the heads off of zombies was enough, regardless of how they looked. Your heart cannot help but feel warm and cuddly as Killing Floor brings out memories of your innocent days.
As for the sounds, why my friend you are in for a treat! Any of the armaments you have to choose from in this piece are accompanied by quite satisfying and appropriate sound effects, enhancing the realism of this game significantly.
As for the gameplay (or should I say gunplay, oho!), Killing Floor will satisfy any of your possible needs (assuming your needs consist of riddling things with bullet holes). Indeed, it is extremely refreshing in this day and age, when so many games are bogged down in petty issues like "story" or "purpose." It forces the brain to take on so much more work, to need to have a REASON to do everything. Killing Floor is unique in that it does away with all of this nonsense. You join a server, you have 3 seconds. Now there are zombies. Kill them all. Next, buy new guns (of which there are many). More zombies are here now. Kill them all. This is Killing Floor. I might add that the guns are extremely satisfying- unlike in less civilized games like Halo, it is impossible to "spray and pray" effectively in Killing Floor. Ammo is extremely scarce (you will most likely run out of your main weapon's ammo every single wave), and the only guns that are fully automatic have relatively small clips. Each gun also has iron sights of some sort or another, which become extremely important when conserving ammo is a must. Also, the guns have effective and satisfying recoil- making each shot you fire feel wonderful.
In short, Killing Floor is the modern art of videogaming. It does away with all the silliness and complication and leaves you with one thing: beauty.